Want to know how to spot an artificial quake? Look at the depth it occurs at. If you look on the USGS site for the depth of the recent (October 25) earthquake off the coast of Honshu Japan it was at 10 KM. It is important for people to realize that NEVER in the history of earthquakes have we EVER had anything significant as shallow as 10 KM, earthquakes typically happen at 70 KM or more.
Any quake that happens at or near 10 KM is now suspect for either a nuclear blast or the earthquake machine.